Terrain conforming track assembly

ABSTRACT

An endless track assembly that mounts to a wheeled vehicle. The assembly provides 1) a track suspension having fixed or adjustable, independently biased sets of idler wheels to vary the track contour without affecting track tension, 2) an eccentric bearing housing at a drive sprocket controls track tension, 3) a contoured peripheral edge at the drive sprocket prevents ice and mud buildup, 4) rubber-coated, plastic idler wheels facilitate track movement, 5) a multi-vehicle compatible adapter mounting plate accommodates a variety of vehicles, 6) a rotation limited torsion coupler and/or rotation limiting coupler arms prevent track contact with the vehicle, 7) a locking steering arm coupler prevents loss of steering control, and 8) shaped track lugs and channels clear and direct debris away from the track suspension and drive assembly. The improved suspension particularly supports sets of idler wheels in pivotal relation to the track support frame and resiliently biases a pre-tensioned rocker arm that links adjacent suspension arms mounted to the adjoining idler wheels. Suspension arm movement induces expansion and contraction of tension springs coupled to the rocker arms to augments shape changes at the track contact surface to optimize traction and steering control.

BACKGROUND OF THE INVENTION

The present invention relates to all terrain vehicles (ATV) and, inparticular, to an improved endless track assembly that can besubstituted for the drive wheels of wheeled ATV's or any two, four orother multi-wheel drive vehicle.

A variety of all terrain vehicles have been developed for recreational,commercial, farm and military use. Such vehicles can include wheelsand/or endless track assemblies to achieve traction over off-roadsurfaces with relatively low surface pressure at the contact surfaces ofthe drive train.

Snowmobiles represent an example of a track-based recreational vehiclethat is used on snow and ice. The tracks, however, are not readilysusceptible to operation over other types of terrain (e.g. abrasive,non-frozen) and use of the vehicle is limited to certain climates andseasons of the year.

A variety of other personal ATV's that support tracks, floatation tiresand/or combinations of tires and tracks are also available for yearround use over woodland, wet and swampy or desert terrain. The drivetrains of the track-based ATV vehicles, like snowmobiles, are typicallydesigned for dedicated use and cannot be readily adapted to alternativeuses. Wheel-based ATV vehicles supported on floatation tires work wellin woodland conditions, but have difficulty traversing snow, swamp anddesert terrain.

An economical conversion assembly is therefore desired to expand theoperational use of wheel-based ATV's and pickup trucks. Examples of sometrack assemblies that can be used to convert 4-wheel drive vehicles totrack vehicles are shown at U.S. Pat. Nos. 3,689,123; 4,448,273; and5,607,210.

The present improved track assembly was developed to accommodate theforegoing need and provides a number of improved features thataccommodate a wide range of vehicles offered by a number of automotiveand ATV manufacturers. Collectively, the improvements permit theconversion of the ATV's over to track operation in a matter of minutes.

The improved track assembly provides 1) a resiliently biased idler wheelsuspension that conforms the shape of the track contact surface toterrain changes, 2) rubber coated, plastic idler wheels, 3) a drivewheel with a radiused peripheral edge to prevent ice and mud buildup, 4)an eccentric track tensioner housing that rotates the track drive wheelto control track tension, 5) a multi-vehicle adapter mounting plate, 6)stop limit flanges at a torsion mounting coupler, 7) a set screwrestrained coupler arm, and 8) track lugs shaped to direct debris awayfrom the track suspension and drive assembly.

SUMMARY OF THE INVENTION

It is a primary object of the invention to provide an endless trackassembly that can be substituted for a wheel of a wheeled vehicle.

It is further object of the invention to provide an improved endlesstrack assembly having an idler wheel suspension that conforms the trackcontact surface to contour changes in the terrain.

It is a further object of the invention to provide a resiliently biasedidler wheel suspension that accommodates changing terrain contourswithout changing the track tension and maintains a relatively small areaof ground contact to facilitate steering.

It is a further object of the invention to independently and resilientlybias multiple groupings of idler wheels to vary the track contour tomaintain track contact with elevated obstructions and depressions andwherein each grouping is independently biased relative to the othergroupings.

It is a further object of the invention to provide a track suspensionwith a pair of idler wheels having an adjustable, complementaryresilient bias (e.g. compression or extension) such that a constantrelative bias can be set and maintained between the idler wheels as thewheels rise and/or fall and correspondingly the track profile changeswith contour changes.

It is a further object of the invention to provide a track suspensionhaving fore and aft idler wheel sets and wherein the idler wheels areindependently biased under compression or extension relative to eachother.

It is a further object of the invention to provide a track support framewith a replaceable drive wheel having teeth protruding to the lateralsides to accommodate tracks having different pitches between the drivelugs.

It is a further object of the invention to provide a drive sprockethaving a contoured peripheral edge shaped to direct ice, mud and otherdebris away from the edge.

It is a further object of the invention to provide an eccentric couplingbetween the frame and track to adjust track tension.

It is a further object of the invention to provide an eccentric housingat the drive sprocket that rotates within a mating aperture at thesupport frame to adjust track tension.

It is a further object of the invention to provide molded plastic idlerwheels coated at a circumferential surface with a material adhesivelycomplementary to the drive track material (e.g. rubber) to enhancegripping between the idler wheels and drive track and with exposedplastic sidewalls that contact and slip within track channels or groovesto minimize track wear.

It is a further object of the invention to provide a drive track whereinthe belting and cords at the peripheral edges of the track areconstructed to cup inward adjacent the sides of the drive sprocket andidler wheels to prevent detachment of the track from the support frame.

It is a further object of the invention to provide a multi-vehicleadapter plate that mounts to the drive sprocket and has shaped surfaces(e.g. contours, holes, slots, recesses, dimples etc.) that mate withdifferent mounting configurations at a number of vehicles.

It is a further object of the invention to provide an anti-torquecoupler between the track assembly and vehicle having first and secondlinkage pieces mounted to pivot relative to one another and whereinflanged surfaces at the linkage pieces limit rotation of the trackassembly relative to the vehicle.

It is a further object of the invention to provide a coupler housingthat mounts to a vehicle steering linkage (e.g. tie rod end or balljoint) and contains a setscrew that cooperates with a contoured surfaceof a mating linkage piece to draw the linkage piece into abutment withthe housing and lock the connections to prevent vibration and loosening.

The foregoing objects, advantages and distinctions of the invention areobtained in the presently preferred track assembly of the invention. Theassembly provides a cast metal support frame having right and leftvertical risers and upper and lower cross beams. An aperture at theupper cross beam supports an eccentric housing mounted to a replaceabledrive sprocket. The eccentric housing extends through a drive frameaperture and upon rotation induces the drive sprocket to establish thetrack tension. Flange arms of the frame at the aperture compressivelycapture the housing and drive sprocket to the support frame to maintainan established track tension.

Lateral arms project from the drive sprocket and engage drive lugs atthe interior of the track. The peripheral edge of the drive sprocket iscontoured to prevent the build-up of ice, mud and debris at the drivesprocket and track grooves. Drive sprockets with different toothspacings can be attached to the frame.

A multi-vehicle adapter plate couples the drive sprocket to a vehicle'slug bolts. Associated suspension linkages couple the track assembly tothe chassis and/or steering surfaces of a variety of different vehicles.

Sets of independently biased, molded plastic, rubber coated idler wheelscooperate with the drive sprocket to support a lugged drive track. Twosets of differing sized idler wheels bias the forward and trailing endsof the drive track to induce changes in the track contact surface thatmimic contour changes in the terrain.

Pivot pins secured to the lower cross beam support a pair of suspensionor swing arms that support the axles of each set of idler wheel axles.Other pivot pins secure one end of a linkage or rocker arm that extendsthrough a channel or bore in the lower crossbeam between the swing arms.A spring, mounted under compression with a threaded adjuster fitted tothe frame, biases the opposite end of the rocker arm. Rotation of eitherswing arm induced by movement of the idler wheels over an elevatedobstruction or into a depression is transferred via the rocker arm tothe other idler wheel and is opposed or assisted as determined by apre-set, adjustable bias at the spring.

A torsion control coupler is secured to one of the vertical risers and apair of linkage pieces extend from a core piece. Flanges at the linkagepieces project to interact as stops to limit the maximum rotation of thetrack assembly. A steering piece mounts between one of the linkagepieces and a coupler housing that captures the steering linkage of thevehicle, for example a tie rod end. A contoured surface of the steeringpiece cooperates with a setscrew at the coupler housing to capture andlock the tie rod end against vibration.

Shaped lugs project from the track interior to define channels for theplastic idler wheels. Lateral uncoated sides of the idler wheels contactthe channel walls and a rubber tread band contacts the track. The lugsscrape debris from the idler wheels and provide surfaces shaped todirect the debris away from the track interior Still other objects,advantages, distinctions and constructions of the invention will becomemore apparent from the following description with respect to theappended drawings. Similar components and assemblies are referred to inthe various drawings with similar alphanumeric reference characters. Thedescription should not be literally construed in limitation of theinvention. Rather, the invention should be interpreted within the broadscope of the further appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an assembled front perspective drawing of the track assembly.

FIG. 2 is an assembled rear perspective drawing of the track assembly.

FIG. 3 is a perspective drawing of the track assembly shown in explodedassembly.

FIG. 4 is a perspective drawing of a row of drive lugs at the interiorsurface of the track.

FIG. 5 is a diagrammatic representation showing alternative idler wheelpositions and related contour changes at the drive track to accommodateelevated obstructions.

FIG. 6 is a diagrammatic representation showing alternative idler wheelpositions and related contour changes at the drive track to accommodatedepressions in the terrain.

FIG. 7 is a diagrammatic representation of a compressively biased idlerwheel suspension.

FIG. 8 is a diagrammatic representation of an idler wheel suspensionbiased with springs mounted in extension.

FIG. 9 is a plan view showing the peripheral edge shape of the drivewheel relative to a drive channel at the track interior.

FIG. 10 is a cross section view showing the peripheral edge shape of anidler wheel relative to a drive channel at the track interior.

FIG. 11 is a diagrammatic representation showing alternative tracktensions at the drive track at different rotations of the eccentricdrive track tensioner.

FIG. 12 is a plan view showing the mounting plate adapter.

FIG. 13 is a perspective drawing showing a two-section coupler to thetorsion control housing.

FIG. 14 is a perspective drawing showing a steering arm coupler housingand control arm.

Similar structure throughout the drawings is referred to with the samealphanumeric reference numerals and/or characters.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to FIGS. 1-3, front, rear and exploded assembly views areshown to the improved track assembly 2 of the invention. Individualtrack assemblies 2 are typically mounted to the drive and non-drivewheels of an ATV, truck or other vehicle to convert the vehicle over tooff road travel over snow, sand and other terrain that requires arelatively low contact surface pressure. The assemblies 2 when adaptedto a typical personal ATV provide a contact surface pressure of lessthan one-pound per square inch. Larger track assemblies 2 can be adaptedto automotive vehicles, such as ½ to 1 ton pickup trucks or even largervehicles.

Each track assembly 2 generally provides a reinforced, endless track 6.The track 6 is typically constructed of rubber with suitable belting andreinforcing fibers to withstand typically encountered terrain, includingrocks, logs, mud, sand etc. The lateral edges of the track areconstructed to cup slightly inward at the extreme peripheral edges, uponsetting a preferred tension. The cupping in the space adjacent exposedsides of adjoining idler wheels facilitates retention of the track tothe suspension.

The outer ground contact surface 8 is provided with an array of lugs 10of desired shapes and sizes that are typically arranged in displacedrows or other desired arrangements. The lugs 10 are generally shaped andlocated to enhance traction and travel over an anticipated terrain. Theinner surface 9 of the track 6 includes a series of rows 12 of laterallydisplaced inner lugs 14 and 16, reference FIG. 4. The lateralseparations between the lugs 14 and 16 define a pair of longitudinalidler wheel channels 18 that are displaced from a center longitudinaldrive wheel channel 20.

The track 6 is suspended around two forward and two aft idler wheels 22and 23 and four inner idler wheels 24. The idler wheels 22-24 (eightidler wheels total) are mounted to the lateral sides of a track frame 26and rotate in the channels 18. The fore and aft idler wheels 22 and 23exhibit a larger diameter (e.g. 8 to 12-inches) than the inner idlerwheels 24 (e.g. 3 to 6-inches).

A rubber tread band or annulus 27 is fitted to the circumferentialsupport surface of each of the idler wheels 22-24 to cushion and providetraction with the inner track surface 9, reference FIG. 10. The band 27can be constructed from a variety of materials and/or may have a contactsurface with the tread surface 9 that is, for example, shaped withgrooves or projections to facilitate contact, traction and rotationrelative to the track 6. The band 27 can be insert molded with thewheels 22-24 or be separately mounted and/or bonded or coated to thewheels 22-24.

The idler wheels 22-24 are constructed from compression-molded plastic,although can be constructed of other materials and/or can be constructedwith other fabrication processes. The idler wheels 22-24 run in thechannels 18 and the relatively slippery plastic sides of the wheels22-24 lie adjacent the vertical sidewalls of the longitudinal grooves18. The plastic slips upon contact with the lugs 10. The wheels 22-24are relatively intolerant to the adhesion of debris, which is readilydischarged from the wheels 22-24 and track interior as discussed below.

A cast aluminum drive wheel or sprocket 28 rides in the channel 20.Lateral flange arms 30 project from the sidewalls of a multi-spoked hub31 and engage the leading surfaces 34 of the lugs 14 and 16 and thedrive track 6. The circumferential edge 29 of the drive wheel 28 isshaped to prevent the buildup of ice and/or debris at the drive wheel28, reference FIG. 9. The edge 29 is particularly contoured to exhibit acompound-arcuate profile configured from several back-to-backquarter-round surfaces. Several relieves or recesses are formed whichcooperate with the channel 20 to dislodge and eject debris.

With attention to FIGS. 4, 9 and 10, the collection of debris is furtherreduced via a cooperative wiping action that occurs as the flange arms30 contact each row 12 of lugs 14 and 16. The leading surface of theadjoining lugs 14 is generally flat and projects orthogonal to the innertrack surface 9 to promote contact with the flange arms 30. Thesidewalls of lugs 14 and 16 at the outer and inner channels 18 and 20,in turn, exhibit tapered surfaces 33 and 35 that flare outward as theyrise from the surface 9. The tapered surfaces 33 of the channel 20scrape and relieve debris that is released from the peripheral edge 29of the drive wheel 28. Recesses 32 at the trailing surfaces of the lugs14 further relieve debris from the drive wheel 28 and/or interior of thetrack 6.

The tapered surfaces 33 and 35 at the channels 18, otherwise, conform tocomplementary tapered plastic sidewalls at the idler wheels 22-24. Anydebris at the idler wheels 22-24 is scraped from the sides of the wheels22-24 as the wheels 22-24 rotate along the channels 18. The plastic torubber contact also provides for less abrasion than experienced withconventional tracks. The leading and lagging vertical walls 34 and 36 ofthe lugs 16 each exhibit compound tapers that project to a flat apex.The walls 34 and 36 also taper as they extend laterally toward thelateral edge of the track 6 such that debris scraped from the idlerwheels 22-24 is directed away from the interior of the track 6. Theidler wheels 22-24 are thus able to run smooth without collecting debrisand possibly dislodging the track 6 from the frame 26.

Returning attention to FIG. 3 and although only two of the eight idlerwheels 22-24 are shown, each track assembly 4 is constructed toresiliently bias the idler wheels 22-24 to follow and conform the track6 to contour changes in the terrain. In a resting condition (shown indashed line), the track frame suspension supports the track 6 to theframe 26 to exhibit a generally isosceles triangular profile, referenceFIGS. 5 and 6. During motion, the idler wheels 22-24 independently andresiliently allow the forward, middle and aft end portions of thetrack's ground contact surface 8 to flex and undulate.

The profile of the track is directed by the idler wheels to maintainsteering control and optimal contact with the terrain such as shown insolid line at FIGS. 5 and 6. This is achieved by independently biasingthe forward and aft sets of the idler wheels 22,24 and 23,24 relative toeach other. The preset bias of each set of idler wheels 22,24 and 23,24is separately adjusted to allow the user to tailor the ride of eachtrack assembly 4.

Movement of the contact surface 8 over an elevated obstruction or into adepression induces the forward idler wheels 22 and the adjacent idlerwheels 24 to rotate and change the track contour. For example and withattention to FIG. 5, if the forward idler wheels 22 rise and rotateclockwise relative to the frame 26, the adjacent idler wheels 24 aredirected to follow clockwise by a rocker arm linkage 78. A resilientbiasing member 86 expands and biases the rocker arm 78 to assist therotation and maintain track contact with the ground.

Alternatively and with attention to FIG. 6, if the forward idler wheels22 follow a depression and rotate counterclockwise relative to the frame26, the following idler wheels 24 are directed to follow by the rockerarm 78. The biasing member 86 is simultaneously compressed to resist therotation. In either instance, the area of the contact surface 8 with theterrain is resiliently optimized, which promotes traction and steeringcontrol. The adjacent aft set of idler wheels 23 and 24 are similarlybiased to ensure track contact.

The forward set of two idler wheels 22 and two adjacent inner idlerwheels 24 are mounted to pivot about the frame 26 and are resilientlybiased with an adjustable, resilience preset by a spring member 86 onthe rocker arm 78. The two aft idler wheels 23 and two adjacent inneridler wheels 24 are mounted to independently pivot about the frame 26and are biased with a separately adjusted, bias member 86 abutting therocker arm 78. As the contact surface 8 negotiates the terrain, theleading and lagging sets of idler wheels 22, 24 and 23,24 cooperate toinduce the track 6 to conform to the terrain.

The manner of mounting the idler wheels 22-24 and drive wheel 28 to thedrive frame 26 is apparent from FIG. 3. The frame 26 provides forwardand aft vertical riser members 42 and 44. Upper and lower cross members46 and 48 connect the riser members 42 and 44. The idler wheels 22-24are secured to the lower cross member 48 and the drive wheel 28 issecured to the upper cross member 46. The mechanical construction andsuspension of each of the forward and aft sets of idler wheels 22, 24and 24, 23 is identical and is described below for only one side of theforward set of wheels 22, 24, but should be understood to be the samefor the aft set.

The forward idler wheels 22 are secured to the bottom of the risermember 42 with an outer suspension arm 50 and a pivot pin 52. Zerkfittings 51 are mounted to the pin 52 to facilitate lubrication of thepivot. The pivot pin 52 extends through apertures 54 in a pair of outerswing arms 56 that extend from a bushing piece 58 and a bore 60 at theriser member 42. The swing arms 56 mount to the lateral sides of theriser member 42. An axle 62 extends through a bore 64 of the bushingpiece 58, seals 57 and bearings 59 and supports the forward idler wheels22.

The inner idler wheels 24 are secured to the bottom of the riser member42 with a suspension arm 66 and another pivot pin 52 outfitted with azerk fitting. The pivot pin 52 extends through apertures 70 in a pair ofswing arms 72 that extend from a bushing piece 74 and a bore 76 at theriser member 42. The swing arms 72 mount to the lateral sides of theriser member 42. An axle 62 extends through a bore 77 of the bushingpiece 74, seals 57 and bearings 59 and supports the inner idler wheels24.

A link arm or rocker arm 78 mounts through a vertical aperture 47 in thecross member 48 and is secured between and to the swing arms 56 and 70with pivot pins 52 that don't contain zerk fittings. The pivot pins 52particularly mount between apertures 82 and 84 at the swing arms 56 and72 and bores 79 and 81 at the rocker arm 78. Forces exerted on either ofthe pairs of idler wheels 22 or 24 relative to the frame 26 istransferred by the rocker arm 78 to the adjoining set of idler wheels.

A spring 86 is mounted in a bore 88 of the riser member 42 and iscontained between an end cap 92 that is secured to the bore 88 and aseat 90 at the link arm 78. The tension or compression of the spring 86is established with a bolt 93 that extends through the riser 42 andcontacts the cap piece 92. Any movement of the idler wheels 22, 23 or 24is thus opposed or assisted in relation to the compression and expansionof the spring 86 in relation to a pre-loaded compression. As the track 6moves to conform to the terrain, the track tension however does notchange with movement of the idler wheel suspension.

FIGS. 7 and 8 separately depict in diagrammatic form two generalizedalternative ways to bias the grouped sets of idler wheels 22,24 and23,24. FIG. 7 demonstrates the compressive mounting of the spring 86shown and used in the preferred embodiment of the assembly 2 anddiscussed with respect to FIGS. 3, 5 and 6. FIG. 8 demonstrates amounting of the spring 86 in extension relative to an intermediateturnbuckle or anchor piece 87. Opposite hooked ends of the turnbuckle 87are independently adjusted to vary the static extension and resilientbias on the springs 86 and the forward and aft sets of idler wheels22,24 and 23,24.

With continuing attention to FIG. 3 and additional attention to thediagrammatic FIG. 11, the tension of the track 6 relative to the idlerwheels 22-23 and drive wheel 28 is separately established with aneccentric mounting of the drive wheel 28 to a bore 94 at the upper crossmember 48. The track tension is particularly established with aneccentric assembly 100 that rotates within the bore 94.

The assembly 100 includes a hub 101 that mounts through a seal 103 andbolts to the drive sprocket 28. An eccentric shaped bearing housing 104extends from the hub 101 and rests in the bore 94. A separate,cylindrical spindle bearing 106 is secured in the housing 104 with asnap ring 105. The housing 104 is retained to the hub 101 with a washer107 and nut 109. A cover or lock cap 99 and seal 97 are secured to theend of the housing 104 with a number of fasteners 15.

Upon loosening carriage fasteners 15 at flanges that depend from thebore 94 beneath the cap 99 and rotating the cap 99 with a wrench 95, thehousing 104 and drive sprocket 28 rotate within the bore 94. Dependingupon the relative rotation of the eccentric housing 104, the drivesprocket 28 stretches or relaxes the tension of the track 6. Once apreferred track tension is established, the fasteners 15 are tightenedto draw the frame 26 at the bore 94 into compression with the bearinghousing 104 to fix the tension on the track 6. It is to be appreciated avariety of other fastening arrangements may be used to secure theestablished position of the housing 104.

The track assembly 2 is typically secured to the vehicle at availablelug bolts that extend from the vehicle wheel and mount to holes 108 atthe hub 101. Due to the wide range of vehicles with which the assembly 2is compatible, a special adapter plate 110 is provided to facilitatemounting the track assembly 2 to each of the vehicles. A presentlypreferred plate 110 is shown at FIG. 12 and mounts between the hub 101and the vehicle drive train, typically the driven or un-driven hubs of aconverted vehicle. The adapter plate 110 is held to the hub 101 with anumber of fasteners 113. Any number of apertures 112, slots 116 and/orraised surfaces 118 or depressions 120 can be provided at the adapterplate 110 to align with a particular mounting geometry of a vehicle. Theadapter plate 110 has particularly been designed to mount to severaldifferent lug bolt arrangements of identified ATV's and allow clearanceover protruding brake inspection covers and other adjoining vehicleparts.

Returning attention to FIG. 3 and with additional attention to FIG. 13,the track assembly 2 is separately secured to the vehicle with a torsioncontrol assembly 122. A pair of coupler arms 121 and 123 or improvedcoupler arms 124 and 126 are secured to the assembly 122. The arms 123and 124 are secured to a pair of brackets 138 with fasteners 125. Thecoupler brackets 138 contain resilient or elastomer shims 140. The arms121 and 126 are separately secured to a cooperating steeririg orstationary surface at the vehicle.

A torque tube 142 extends from an appropriate one of two apertures 144in the risers 42 and 44 and is secured to the drive frame 26 with boltand nut fasteners 141 and 143. The torque tube 142 might also be securedto the risers 42 and 44 with a variety of n alternative fasteners. Forexample, the tube 142 might include spring pins or other projectionsthat snap into mating apertures or recesses provided at the apertures44.

An outer section of the torque tube 142 nests in the shims 140. A flaredouter end of the torque tube 142 retains the torque tube 142 at anequilibrium condition in the brackets 138. Clockwise andcounterclockwise Rotation of the torque tube 142 is resisted by theshims 140 and thereby prevents contact between the track assembly 2 andthe vehicle.

Where the coupler arms 124 and 126 of FIG. 13 are used to couple thetrack assembly 2 to a vehicle, stop flanges 128 and 130 are provided tolimit the maximum rotation of the track assembly 2. That is, the stopflanges 128 and 130 limit rotation of the arm 126 relative to thesurfaces 132 and 134 at the arm 124. As the arms 124 and 126 normallyrotate, the flanges 128 and 130 contact the surfaces 132 and 134 toprevent over-rotation of the assembly 2 relative to the assembly 122 andcontact with the vehicle.

Where the arm 126 couples to a steering surface of the vehicle, such asa tie rod end, an improved locking coupler 150 shown at FIG. 14 ismounted to the arm 126. The coupler 150 prevents possible loosening ofthe critical steering connection. The coupler 150 provides a housing 152having a locking bar 154 that is welded to the housing 152. The housing152 captures the vehicle's tie rod end to the end of a steering arm 155that separately connects to a vehicle steering surface. Theconfiguration of the housing 152 and arm 154 can be varied toaccommodate different types of tie rods.

The housing 152 is typically secured to the vehicle with a fastenerbetween an aperture 156 at the locking arm 154 and the aperture 146 ofthe coupler arm 126. A vehicle tie rod end (not shown) mounts through anaperture 158 in the housing 152, which can be hexagonal shaped and/orinclude flat surfaces that align with flat surfaces at the tie rod end,and an aperture 160 in the vehicle steering arm 155.

The connection is locked or prevented from loosening upon separatelysecuring a setscrew 162 at the locking bar 154 to contact a surface 164of the arm 155 and draw the arm 154 and the tie rod end to the housing152. A nut (not shown) separately secures the tie rod to the housing152. An additional brace (not shown) may also be fitted between thehousing 152 and adjoining suspension components of the vehicle to helpsupport the steering arm 155.

While the invention has been described with respect to a number ofpreferred constructions and considered improvements or alternativesthereto, still other constructions may be suggested to those skilled inthe art. It is also to be appreciated that selected ones of theforegoing features, for example, the independently biased idler wheelsuspension, contoured drive sprocket, eccentric tensioner, rotationlimited torsion coupler and/or steering coupler arms, can be usedsingularly or can be arranged in different combinations to provide avariety of improved track assemblies. The foregoing description shouldtherefore be construed to include all those embodiments within thespirit and scope of the following claims.

1. An endless track assembly for a vehicle comprising: a) a frameincluding a drive aperture; b) first and second suspension arms mountedto pivot from said frame and each supporting an axle; c) a plurality ofidler wheels mounted to said frame and wherein a first idler wheel ismounted to the axle of said first suspension arm and a second idlerwheel is mounted to the axle of said second suspension arm, wherein alinkage arm is coupled between said first and second suspension arms,and wherein a spring is mounted to bias movement of said linkage arm,such that a pivotal movement of either of said first and second idlersuspension arms is resiliently opposed or assisted by said spring as theother of said first and second idler wheels attempts to follow; d) adrive sprocket mounted to said drive aperture; and e) an endless tracktrained around said drive sprocket and said plurality of idler wheels,whereby undulations in the terrain are followed by pivotal rotation ofsaid idler wheels to vary the longitudinal profile of said track,without effecting track tension, to complement the undulations.
 2. Atrack assembly as set forth in claim 1 wherein said spring is mounted ina bore of said frame and wherein an adjuster member abuts said spring toestablish a preset compression of said spring.
 3. A track assembly asset forth in claim 1 wherein said spring is mounted to said frame andwherein an adjuster member is coupled to said spring to establish apreset extension of said spring.
 4. A track assembly as set forth inclaim I wherein a housing having an eccentric surface is secured to saiddrive sprocket and mounted in said drive aperture such that rotation ofsaid housing in said drive aperture varies the tension of said track. 5.A track assembly as set forth in claim 4 wherein said eccentric housingSupports a bearing and is adapted for rotation with a wrench, andwherein a member fastened to said frame compressively secures saidhousing to said frame to retain a selected rotation of said eccentrichousing.
 6. A track assembly as set forth in claim 1 including torsionmeans for biasing said track assembly to an equilibrium position andlimiting the relative rotation of said track assembly to said vehicle toprevent contact therebetween.
 7. A track assembly as set forth in claim6 including a linkage for coupling said torsion means to said vehicleand wherein a first coupler arm includes first and second flangedsurfaces that contact first and second surfaces of a second coupler armto define first and second stop limits and a range of relative rotationof said track assembly to said vehicle.
 8. A track assembly as set forthin claim 1 wherein a housing having an eccentric surface is secured tosaid drive sprocket and mounted in said drive aperture such thatrotation of said housing in said drive aperture varies the tension ofsaid track and including torsion means for biasing said track assemblyto an equilibrium position and limiting the relative rotation of saidtrack assembly to said vehicle to prevent contact therebetween.
 9. Atrack assembly as set forth in claim 1 including an adapter plate thatmounts to said drive sprocket and is configured to mount to a pluralityof vehicles.
 10. A track assembly as set forth in claim 1 wherein saidtrack includes a plurality of outer lugs that project from an interiorsurface of said track along lateral outer edges of said track andcontact outer surfaces of said idler wheels and wherein said lugsinclude leading and lagging tapered surfaces that collectively exhibitan inverted V-shape as they rise from the interior surface to a flatapex surface and which apex surface exhibits declines as it extendstoward an outer lateral track edge, whereby said lugs direct debrisupward and outward from the interior of said track.
 11. A track assemblyas set forth in claim 10 including a plurality of interior lugs andwherein said idler wheels are constructed of plastic, wherein acircumferential surface of each of said idler wheels includes a rubberannulus that contacts the interior surface of said track, and whereinuncoated sides of said idler wheels rotate within channels definedbetween said outer lugs and adjacent interior lugs.
 12. A track assemblyas set forth in claim 1 wherein a peripheral edge of said drive sprocketexhibits a contoured profile that includes a plurality of radiusedreliefs relative to an inverted V-shaped drive channel having a flatapex between adjacent lugs that rise from an interior surface of saidtrack, whereby said sprocket directs debris away from said drivechannel.
 13. A track assembly as set forth in claim 1 including acoupler housing that couples to a steering member of said vehicle andwherein the housing includes a fastener mounted to said housing to drawsaid steering member into compression with said housing.
 14. An endlesstrack assembly comprising: a) a frame including a drive aperture; b)first and second and third and fourth suspension arms mounted to pivotfrom said frame and each supporting an axle; c) a plurality of idlerwheels, wherein pairs of first and second idler wheels are mounted tothe axles of said first and second suspension arms and pairs of thirdand fourth idler wheels are mounted to the axles of said third andfourth suspension arms, wherein a first linkage arm is coupled betweensaid first and second suspension arms and a second linkage arm iscoupled between said third and fourth suspension arms, and wherein firstand second springs bias movement of said first and second linkage arms,such that a pivotal movement of any of said pairs of first and secondand third and fourth idler wheels is resiliently opposed or assisted bysaid first and second springs as the other pair of said first and secondand third and fourth idler wheels attempts to follow; d) a drivesprocket mounted to said drive aperture; and e) an endless track trainedaround said drive sprocket and said plurality of idler wheels, wherebyundulations in the terrain are followed by pivotal rotation of saididler wheels to vary the longitudinal profile of said track, withouteffecting track tension, to complement the undulations.
 15. A trackassembly as set forth in claim 14 wherein said first and second springsare mounted to said frame and wherein an adjuster member is coupled tosaid spring to vary the compression of said first and second springsrelative to said first and second linkage arms.
 16. A track assembly asset forth in claim 14 wherein said first and second linkage arms areeach supported in a bore of said frame, wherein said first and secondsprings are mounted in first and second bores of said frame and whereinfirst and second adjuster members are coupled to said first and secondsprings to vary the compression of said first and second springsrelative to said first and second linkage arms.
 17. A track assembly asset forth in claim 14 wherein a housing having an eccentric surface issecured to said drive sprocket and mounted in said drive aperture suchthat rotation of said housing in said drive aperture varies the tensionof said track.
 18. A track assembly as set forth in claim 17 wherein acap is fastened to said eccentric housing and wherein a wrench mounts torotate said cap and eccentric housing and such that upon securingfasteners secured to said frame said eccentric housing is compressivelysecured to said frame.
 19. A track assembly as set forth in claim 14including torsion means for biasing said track assembly to anequilibrium position and limiting the relative rotation of said trackassembly to said vehicle to prevent contact therebetween.
 20. A trackassembly as set forth in claim 19 including a linkage for coupling saidtorsion means to said vehicle and wherein a first coupler arm includesfirst and second flanged surfaces that contact first and second surfacesof a second coupler arm to define first and second stops and a range ofrelative rotation of said track assembly to said vehicle.
 21. A trackassembly as set forth in claim 14 wherein said spring is mounted to saidframe and wherein an adjuster member is coupled to said spring to varythe extension of said spring.
 22. An endless track assembly comprising:a) a frame including a drive sprocket and a plurality of idler wheelsmounted to said frame; b) an endless track trained around said drivesprocket and said plurality of idler wheels; c) a housing secured tosaid drive sprocket and mounted to rotate in said frame and wherein saidhousing has an eccentric surface and said eccentric surface contactssaid frame such that rotation of said housing varies the tension of saidtrack; and d) a fastener for securing said housing at a selectedrotation.
 23. A track assembly as set forth in claim 22 wherein saidhousing supports a bearing, wherein a cap is fastened to said housing,and wherein a wrench mounts to rotate said cap and eccentric housing andsuch that upon securing fasteners secured to said frame said eccentrichousing is compressively secured to said frame.
 24. An endless trackassembly comprising: a) a frame including a drive sprocket and aplurality of idler wheels mounted to said frame; and b) an endless tracktrained around said drive sprocket and said plurality of idler wheels,wherein said track includes a plurality of lugs that project in aplurality of rows from an interior surface of said track and define aplurality of longitudinal channels within which said drive sprocket andsaid plurality of idler wheels move, and wherein a plurality of lugsalong lateral outer edges of said track that contact outer surfaces saididler wheels include leading and lagging tapered surfaces that exhibitan inverted V-shape as they rise from the interior surface to a flatapex surface and which apex surface declines as it extends toward anouter lateral track edge, whereby said lugs direct debris upward andoutward from the interior of said track.
 25. A track assembly as setforth in claim 24 wherein said idler wheels are constructed of plastic,wherein a circumferential surface of each of said idler wheels includesa rubber annulus that contacts the interior surface of said track, andwherein uncoated sides of said idler wheels rotate within channelsdefined between said outer lugs and adjacent interior lugs.